Traditional incandescent light bulbs are available in various designs such as plain functional bulbs with different glass finishes (e.g. transparent, diffuse or colored) and decorative bulbs with complex filaments, wherein the filament itself serves a decorative purpose. However, due to demands on power saving in lighting devices, driven by eco awareness and legislation, traditional incandescent light bulbs are being replaced by more power efficient light sources such as fluorescent lamps and LED (light emitting diode) lamps. Such conventional eco-friendly lamps do not provide the same various designs as traditional incandescent light bulbs.
A solution of how to provide a lighting device resembling a carbon filament lamp is disclosed in WO 2006/035349. The document shows a lighting device comprising a solid state light source optically coupled to an optical fiber having an out-coupling surface. A drawback with such a lighting device is that it does not provide a sufficiently energy-efficient functional lighting (such as e.g. general lighting or task lighting).